On Wed, Dec 21, 2016 at 4:06 PM, Jason Merrill <ja...@redhat.com> wrote:
> The last patch implements paper P0522, which resolves DR150 to clarify
> that default arguments do make a template suitable as an argument to a
> template template-parameter based on a new rule that the
> template-parameter must be more specialized (as newly defined) than
> the argument template. This is a defect report that will apply to all
> standard levels, but since we're in stage3 I limited it by default to
> C++17 for GCC 7; it can also be explicitly enabled with
> -fnew-ttp-matching.
And this adds a feature-test macro I proposed to SG10.
commit 2396126078c49cc17dacc905969febd1bdd7caa6
Author: Jason Merrill <ja...@redhat.com>
Date: Thu Dec 22 13:11:26 2016 -0500
Feature-test macro for P0522R0, matching of template template arguments.
* c-cppbuiltin.c (c_cpp_builtins): Define
__cpp_template_template_args.
diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index e2419e8..a841e53 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -985,6 +985,8 @@ c_cpp_builtins (cpp_reader *pfile)
cpp_define_formatted (pfile, "__STDCPP_DEFAULT_NEW_ALIGNMENT__=%d",
aligned_new_threshold);
}
+ if (flag_new_ttp)
+ cpp_define (pfile, "__cpp_template_template_args=201611");
}
/* Note that we define this for C as well, so that we know if
__attribute__((cleanup)) will interface with EH. */
diff --git a/gcc/testsuite/g++.dg/cpp1z/feat-cxx1z.C
b/gcc/testsuite/g++.dg/cpp1z/feat-cxx1z.C
index 086fd25..f61b9f5 100644
--- a/gcc/testsuite/g++.dg/cpp1z/feat-cxx1z.C
+++ b/gcc/testsuite/g++.dg/cpp1z/feat-cxx1z.C
@@ -398,6 +398,12 @@
# error "__cpp_structured_bindings != 201606"
#endif
+#ifndef __cpp_template_template_args
+# error "__cpp_template_template_args"
+#elif __cpp_template_template_args != 201611
+# error "__cpp_template_template_args != 201611"
+#endif
+
#ifdef __has_cpp_attribute
# if ! __has_cpp_attribute(maybe_unused)
